CN109088030B

CN109088030B - Closed porous ceramic composite material and preparation method and application thereof

Info

Publication number: CN109088030B
Application number: CN201810663451.1A
Authority: CN
Inventors: 许瑞; 许刚; 赖旭伦
Original assignee: Dongguan Xinrui Energy Technology Co ltd; Dongguan Saipuke Electronic Technology Co ltd
Current assignee: Dongguan Xinrui Energy Technology Co ltd; Dongguan Saipuke Electronic Technology Co ltd
Priority date: 2018-06-25
Filing date: 2018-06-25
Publication date: 2021-07-27
Anticipated expiration: 2038-06-25
Also published as: CN109088030A

Abstract

The invention relates to a closed porous ceramic composite material and a preparation method and application thereof. The closed porous ceramic composite material of the invention is characterized in that the open pores of the porous ceramic are filled and closed by organic matters, and further made into a porous ceramic isolating membrane. Compared with the existing diaphragm materials of the same type, the porous ceramic isolation membrane prepared by the technology has the advantages of good liquid-carrying property, good coating adhesive force, good heat dissipation property and the like, can be widely applied to the fields of power batteries (xEV), intelligent mobile terminals (3C), energy storage power stations (ESS) and the like, shows excellent wetting property, is beneficial to light weight and miniaturization of finished products of lithium ion batteries, and has obvious economic effect.

Description

Closed porous ceramic composite material and preparation method and application thereof

Technical Field

The invention relates to a preparation technology of a lithium battery, in particular to a preparation method and application of a closed porous ceramic composite material.

Background

Along with the rise of smart phones, smart cars and new energy cars in recent years, more and more mobile devices become data acquisition points and integration points of big data, the Internet of things and the like. The mobile equipment has the advantages that the running speed is higher and higher, the energy consumption is higher and higher, and the mobile equipment is portable and multifunctional along with the improvement of the physical life of people when the energy is provided for the mobile terminal. Taking a mobile phone as an example, a smart phone has replaced a home television to become the first screen of people's life. With the intellectualization and the electromotion of automobiles in the future, the intelligent automobile can possibly become a second screen of daily life of people. Similarly, lithium ion secondary batteries are also being developed for weight reduction, high capacity, rapid charge/discharge, and safety. However, the lithium batteries currently used are all polymer lithium ion batteries (i.e., lithium ion batteries using polymer components in the positive electrode and the negative electrode of the lithium battery), and liquid electrolytes are generally used. The lithium battery faces the following problems in the process of thinning.

One is insufficient rigidity of the battery. The light and thin lithium battery can only be served by a soft package battery usually, the common steel shell battery and 18650 type cylindrical battery (the diameter is 18mm, and the use thickness of the battery) are gradually replaced by the soft package battery due to large volume, low energy density and the like, but the soft package battery is prepared by winding a positive plate, an isolation film and a negative plate, no other binding structures exist among the positive plate, the battery is soft in the use process, the positive and negative plates can slide relatively, and when no negative/positive active substance exists at the corresponding position of the positive/negative plates, serious safety risk can be caused, so that the use safety is influenced.

Secondly, the lithium ion channel is incomplete due to insufficient carrying capacity of the diaphragm, the diaphragm is a film formed by drawing/pre-forming holes on composite films such as polyethylene, polyethylene/polypropylene and the like, the thickness of the film is usually only about 10 mu m, and the surface tension of the polyethylene solid is 31 xl 0^-5N/cm, poor wettability to organic solvent components in the electrolyte, resulting in that the liquid electrolyte cannot sufficiently wet the separator despite the injection of the liquid electrolyte into the lithium ion battery, and it can be known from the working principle of the chemical battery that the separator, which is not actually wetted, blocks a part of lithium ions from passing in and out of the passages of the positive and negative electrodes, resulting in unsatisfactory charge and discharge performance, high and low temperature performance, and cycle performance of the lithium ion battery.

And thirdly, the fragile membrane has safety risk, the thickness of the membrane is usually between 6 and 20 mu m, and the processing process of the membrane is usually dry stretching and dry calendering plus leaching pore-forming process. The prepared diaphragm has certain processing stress (stretching, cutting, winding/unwinding and the like), can shrink again in the using process to eliminate the processing stress, and shrinks more obviously when the temperature rises, so that the internal short circuit of the lithium battery can be caused under the condition of accidental abuse to cause serious safety accidents.

Various solutions are proposed by many experts aiming at the above situation, one of the solutions is an all-solid-state lithium ion secondary battery, namely, a solvent component with low molecular weight in a leaked electrolyte is eliminated, and actually, the all-solid-state lithium ion battery is too expensive and inferior to a liquid electrolyte lithium battery in performance under the current technical conditions, so that some lithium ion battery manufacturing technologies with low price, easy availability and reliable safety performance are urgently needed, and the method belongs to active protection. Another method is to add external Protection (PID)/(CID), Vent, etc., i.e., monitoring, diagnosis, isolation and protection of the battery in an accident situation by an external protection/management system (BMS), which is mainly passive protection.

From the above analysis, many structures of the lithium battery need to be solved from the positive plate, the negative plate and the diaphragm, and the diaphragm between the positive plate and the negative plate is the key to solve the problem.

Many publications and patent documents have proposed methods for improving the safety and service properties of lithium ion batteries by means of membrane structures.

Japanese patent laid-open publication No. 2005-183179 discloses a method of forming Al on the surface of a negative electrode₂O₃，SiO₂，TiO₂The porous insulating layer is formed of the material. Japanese patent laid-open publication No. 2002-231221 discloses a technique for forming a porous lithium dielectric on a surface of at least one of a positive electrode and a negative electrode, for increasing a specific capacity of the negative electrode. Japanese patent laid-open No. 6-36800 discloses a method of forming TiN, Al on the surface of the negative electrode facing the positive electrode₂O₃And the porous insulating film prevents formation of lithium dendrites in the negative electrode. Patent CN102881951A discloses a method for coating Al with a thickness of 0.1-8 μm on a positive/negative electrode sheet₂O₃A method of coating. Patent CN101401232B discloses a granular BaTiO with a dielectric constant greater than 5₃，Al₂O₃，SiC，TiO₂，ZrO₂Formed on at least one surface of the electrode, and having a particle diameter (D)_v50): 0.001 to 10 μm, and the adhesive is oxyethyl pullulan, amino-containing substance, or the like. It can swell with electrolyte, and the thickness of the whole film is 0.01-100 μm. The above patent adopts a pole piece coating method, generally, double-sided unequal-length interval coating exists in the pole piece preparation process, and the pole piece needs to be subjected to processing procedures such as rolling, slitting and the like, and generally, the longer the processing procedure is, the lower the product goodness rate is, so that the application is not suggested.

In patent CN101044644A, CN103633271A, and CN102195020A, in order to improve the thermal stability of the isolation film, 1 to 99 wt% of polymer particles with a higher melting point and a thermal inertia diameter less than or equal to 1 μm are added into the existing basic isolation film composition, and the polymer particles can prevent the external temperature of the battery from being less than 100 ℃ from room temperature within 25s after the battery is nailed, that is, when an internal short circuit occurs, because the isolation film contains the particles with a high melting point, the isolation film can be properly reinforced, and the time for the isolation film to completely melt and short circuit can be properly prolonged, thereby ensuring that the battery will not be thermally out of control. Patent CN102942831B discloses a coating composition for a release film and a preparation method thereof. The coating composition comprises heat-resistant resin and inorganic non-conductive insulating particles, wherein a molecular chain of the heat-resistant resin contains hydrophilic/lipophilic structural units, the thermal decomposition temperature is higher than 250 ℃, a hydrophilic part mainly contains acrylic derivatives and accounts for 50-80 wt% of total functional groups, the lipophilic part mainly contains one or more of acid anhydride, amino and the like and accounts for 20-50 wt%, the inorganic particles are silicate compounds, and inorganic substances account for 60-95 wt% of the total solid matter content of the coating. Patent CN1868077A discloses a flexible, perforated support with a ceramic coating, containing 75 to 99ppm (particle size D)_v50: 0.5 to 10 μm of a material selected from ZrO₂，SiO₂And Al₂O₃And 1-25 ppm (particle size 0.5-10 μm) Y-type zeolite particles. The carrier is porous fiber fabric similar to dust-free cloth, and the thickness of the carrier is less than 50 μm. Patent CN101326658B discloses an organic/inorganic complex with morphological gradientAnd (4) closing the diaphragm. Inorganic particles and an adhesive are applied on one or two porous substrates, the dielectric constant of the inorganic particles is larger than 5, the particle size is 0.001-10 mu m, the adhesive comprises a first type of cyano-group and a second type of adhesive comprising polyvinylidene fluoride, polymethyl methacrylate, carboxymethyl cellulose sodium (CMC) and the like, powder falling in the processing process due to insufficient strength of the coating is avoided, and the thickness of the substrate film is 1-100 mu m. Patent CN100474661C discloses a separator coated with electrolyte soluble polymer, when the battery is injected with electrolyte, the polymer is dissolved to become a part of the electrolysis, which is mainly cyanoethyl compounds, such as cyanoethyl vinyl alcohol, cyanoethyl cellulose, etc., and the polymer is coated on the separator by dipping, molding, rolling, scraping, etc., and another benefit of adding this polymer is to improve the wetting performance of the separator to the electrolyte. Patent CN103811702A discloses a preparation method of a novel ceramic coating polyolefin composite membrane. The ceramic coating comprises porous ceramic particles, inorganic filler and adhesive, the adhesive is dissolved firstly, then ceramic powder and the filler are dispersed in the adhesive to form slurry, then the isolating membrane is coated with single layer or double layers, and the product is obtained after drying and curing. The porous ceramic is one or more of aluminum oxide, aluminum hydroxide, aluminum nitride, magnesium oxide, boron nitride, boehmite, silicon oxide, titanium oxide, zirconium oxide and zeolite particles, the particle size is 0.3-1.2 mu m, and the adhesive is one or a compound of more of acrylic emulsion, acrylate emulsion, butylbenzene emulsion, silane coupling agent and fluororesin. The inorganic substance mostly comprises 40-80 wt% of ceramic, the using amount of the adhesive is 1-10 wt% of the inorganic substance, the thickness of the base material diaphragm is 9-30 mu m, the heat resistance of the inorganic substance is more than 400 ℃, and the thermal conductivity is more than or equal to 20W/(m & lt K & gt). Patent CN103811702A discloses a novel ceramic coated polyolefin composite membrane prepared by porous ceramic particles, inorganic filler and adhesive. The above patents and documents relate to preparation and treatment methods related to separators, and improvement of safety structures of lithium ion batteries.

The ceramic powder is the main raw material of the common isolating coating with low price and stable performance at present, and the true density of the ceramic powder is comparatively high (for example, the aluminum oxide is 3.97 g/cm)³) The density of the coating is much higher than that of solvent water, and physical sedimentation is often generated to cause coating quality fluctuation when the coating is prepared into coatable slurry and used in a standing state; the density of the adopted porous ceramic powder is 2.0g/cm³On the left and right sides, the anti-settling property of the slurry is improved a lot relatively, but the specific surface of the porous ceramic powder is large, the oil absorption value is high, a large amount of non-conductive adhesive is consumed during the preparation of the slurry, the diaphragm can lose the ion conduction effect, and the actual application effect is not ideal.

Disclosure of Invention

The problems of the prior art solved by the invention are as follows: in the prior art, the specific surface of the porous ceramic powder is large, the oil absorption value is high, a large amount of non-conductive adhesive is consumed during slurry preparation, the ion conduction function of an isolating membrane can be lost, and the actual application effect is not ideal. In addition, the existing isolating membrane has small electrolyte carrying amount, insufficient strength under the use condition and insufficient hardness after the lithium ion battery is thinned.

After intensive research, the inventors of the present invention have considered that improvement of a lithium battery separator needs to be undertaken from the following aspects: on one hand, the liquid carrying performance of the diaphragm needs to be improved, on the other hand, the strength of the diaphragm needs to be enhanced, and the diaphragm and the positive/negative pole pieces are preferably bonded together to avoid relative sliding between the diaphragm and the positive/negative pole pieces, so that the service performance and the safety performance of the lithium battery are improved. The inventor creatively carries out obturator treatment on the porous ceramic powder, prepares slurry coating, and removes obturator agent from the coated isolating membrane through leaching so as to re-form the porous ceramic isolating membrane, thereby providing a solution for producing high-safety and high-hardness lithium ion batteries and expanding the application scene of the lithium ion batteries.

Specifically, the invention provides the following technical scheme:

in one aspect, the present invention provides a closed porous ceramic composite material, wherein the open pores of the porous ceramic are closed by filling with an organic material.

Preferably, the closed porous ceramic composite material is one or more selected from the group consisting of an oxide, a nitride, a carbide, a fluoride, a carbonate, and a phosphate; preferably, the porous ceramic is selected from one or more of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, barium oxide, magnesium oxide, yttrium oxide, samarium oxide, ytterbium oxide, boehmite, titanium nitride, aluminum nitride, silicon nitride, calcium phosphate, silicon carbide and magnesium fluoride, and more preferably, the porous ceramic is selected from aluminum oxide and/or silicon dioxide.

Preferably, the closed porous ceramic composite material is one in which the porous ceramic has a particle size of 4.5 μm or less, preferably 0.2 to 4.5 μm, and more preferably 0.5 to 2.3 μm.

Preferably, in the closed porous ceramic composite material, the organic material is selected from a plasticizer and/or silicone oil; preferably, the plasticizer is selected from carboxylic acid esters and/or phosphoric acid esters; the silicone oil is selected from one or more than two of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, methyl phenyl silicone oil, methyl chlorphenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoro propyl silicone oil, methyl vinyl silicone oil, methyl hydroxyl silicone oil, ethyl hydrogen-containing silicone oil, hydroxyl hydrogen-containing silicone oil, cyanogen-containing silicone oil, amino modified silicone oil, epoxy modified silicone oil, polyether modified silicone oil, carboxyl modified silicone oil, alcohol light-based modified silicone oil and phenol light-based modified silicone oil; more preferably, the silicone oil is one or two or more selected from the group consisting of methyl silicone oil, ethyl silicone oil, and amino silicone oil.

Preferably, the closed porous ceramic composite described above, wherein the plasticizer is one or more selected from the group consisting of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diisobutyl phthalate, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, di (2-ethylhexyl) phthalate, tributyl phosphate, triethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, diisononyl adipate and di (2-ethylhexyl) adipate; preferably, the plasticizer is one or more selected from the group consisting of di (2-ethylhexyl) phthalate, dioctyl phthalate, dibutyl phthalate and diisononyl phthalate.

In another aspect, the present invention provides a ceramic separator prepared from a raw material comprising any one of the above-described closed porous ceramic composite materials.

Preferably, the ceramic separator is characterized in that the raw material includes a binder, a thickener, and a separator.

Preferably, the ceramic separator is obtained by mixing a closed porous ceramic composite, a binder and a thickener and then coating the mixture on a separator.

Preferably, the ceramic separator is one or more selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene ethylene copolymer, styrene-butadiene latex, polyacetonitrile, polymethyl methacrylate, polyamide, gelatin, polyvinyl alcohol, polyacrylate, and polyacrylic acid, and preferably, the binder is one or more selected from the group consisting of polyvinylidene fluoride and/or styrene-butadiene latex.

Preferably, in the ceramic separator, the thickener is one or more selected from the group consisting of polyacrylate, acrylic acid copolymer, polyvinylpyrrolidone, cellulose-based compound, and polyacrylamide; preferably, the thickener is one or more selected from the group consisting of methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose and hydroxypropylmethylcellulose.

Preferably, the ceramic separator is one or more selected from the group consisting of a dry-stretched separator, a wet-leached separator, and a textile-prepared fibrous separator; preferably, the separator is one or more selected from the group consisting of polyolefin, polyamide, polyester, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride; it is further preferable that the thickness of the separator is 4 to 30 μm.

Preferably, the ceramic isolating membrane has an axial shrinkage rate of less than 5% and a shrinkage rate in an extension direction of less than 2% after being subjected to a baking test at 60 +/-2 ℃/36 h; it is further preferable that the axial shrinkage rate is less than 10% and the shrinkage rate in the stretching direction is less than 5% by baking test at 110 ℃ +/-2 ℃/1 h.

Preferably, the ceramic separator has an electrolyte wetting angle of 20 ° or less at 20 s.

On the other hand, the invention provides a preparation method of the ceramic isolating membrane, which comprises the following steps:

step a) pulping, namely fully mixing raw materials containing the closed porous ceramic composite material, the binder and the thickening agent in any one of claims 1 to 5 to obtain slurry;

step b) coating, namely coating the slurry prepared in the step a) on a diaphragm and drying;

step c) leaching, namely extracting the isolating membrane obtained in the step b) by using a solvent and drying; and

step d) rolling, namely rolling the isolating membrane obtained in the step c) to obtain a finished product;

wherein step d) may be omitted.

Preferably, in the preparation method, the thickener is added in an amount of 2-5wt%, preferably 3-4wt% of the ceramic powder; it is further preferred that the amount added is 4 to 15 wt%, preferably 8 to 13 wt% of the ceramic powder.

Preferably, in the above preparation method, the ceramic powder accounts for 89 to 93wt% of the dry matter content of the coating composition on the separator.

Preferably, in the above preparation method, in the step b), the coating is one or more selected from printing, dipping, spraying, and extruding; preferably, the separator is coated on one side or both sides; it is further preferred that the coating thickness obtained by drying is 0.5 to 5.0. mu.m.

Preferably, in the above production method, the solvent is one or more selected from acetone, ethanol, butanol and/or isopropanol. Benzene and dimethyl ether should be eliminated as the solvent, which is not environment-friendly on one hand, and may damage the isolation membrane body on the other hand.

Preferably, in the above preparation method, the drying in step b) is drying, and preferably, the drying is performed by using clean gas at a temperature of 40-95 ℃.

Preferably, in the above preparation method, the winding in step d) is controlled by tension, and preferably, the tension strength is 2 to 10N/m. The separator is a porous plastic film (i.e., a piece of broken cloth), and if the tension is too high, the separator will be torn or the pores of the separator will be broken (local breakage), and in addition, the tension will have stress, and the separator will shrink when placed later. Too low a tension the separator was not flat and the coating thickness was not uniform when applied.

The method of carrying out pore closing treatment on the porous ceramic powder in advance and then coating can reduce the using amount of the insulator adhesive, and the pore closing agent is removed by leaching the isolating membrane to form a porous ceramic isolating membrane structure again, so that the liquid carrying amount and the wettability of the isolating membrane can be effectively improved.

On the other hand, the invention also provides the ceramic isolating membrane prepared by any one of the preparation methods.

In another aspect, the invention further provides a lithium ion battery, which comprises any one of the ceramic isolating membranes.

On the other hand, the invention also provides the application of any one of the closed porous ceramic composite materials or any one of the ceramic isolating membranes or the lithium ion battery in the field of energy.

The beneficial effects obtained by the invention are as follows:

according to the invention, the porous ceramic powder is adopted, so that the sedimentation defect caused by solid-liquid density difference can be reduced when the slurry is prepared, the dosage of an adhesive is reduced by introducing a pore closing agent in the slurry preparation process, and the pore closing agent is removed by an extraction method to form the isolating membrane with the porous coating structure, so that the non-wettability of the high-molecular diaphragm is effectively overcome, and the liquid carrying capacity of the isolating membrane is improved. The method is simple and feasible, overcomes the defects of the existing ceramic isolating membrane, and has multiple practical and beneficial effects.

Meanwhile, the invention also provides an application effect of the isolation membrane material in the field of lithium ion batteries, has better cost performance, is particularly suitable for the preparation of the lithium ion batteries in the fields of compact structure, thin thickness requirement, high safety requirement, 3C, xEV, ESS and the like, and expands the application prospect of the lithium ion batteries.

Drawings

FIG. 1-a Scanning Electron Microscopy (SEM) of the separator of example 2, wherein the magnification is 10000 times.

FIG. 1-b Scanning Electron Microscopy (SEM) of the separator of example 3, wherein the magnification is 10000 times.

FIG. 1-c Scanning Electron Microscopy (SEM) of comparative example 2 separator at a magnification of 10000.

FIG. 1-d Scanning Electron Microscopy (SEM) of the separator of comparative example 3, wherein the magnification is 10000 times.

FIG. 2 is a graph showing pore size distributions of examples 5 and 6 and comparative examples 5 and 6.

FIG. 3 is a graph of the electrochemical impedance spectra of the symmetric cells of example 3, comparative example 3, and comparative example 7-2.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The term "plasticizer" as used herein is selected from carboxylic acid esters and/or phosphoric acid esters, excluding silicone oils.

The term "silicone oil" used herein is understood to be synonymous with "silicone fluid", and is a polymer having a siloxane bond (-Si-O-Si-) as a main chain, and is generally in a liquid state at ordinary temperature (25 ℃).

The term "separator" of the present invention is an insulating material not coated with the ceramic powder of the present invention, and the term "insulating film" is an insulating material coated with the ceramic powder of the present invention.

The invention provides a preparation method and application of a porous ceramic isolating membrane.

The porous structure of the porous ceramic isolating membrane is sealed by the obturator in advance before the slurry is prepared, so that the using amount of an adhesive can be reduced when the slurry is prepared, the isolating membrane coated with the porous ceramic is leached to remove the obturator, and the porous ceramic structure is obtained again, so that the liquid carrying performance of the isolating membrane is improved, meanwhile, the lightening and thinning of the lithium ion battery can be promoted, the safety performance of the lithium ion battery can be improved, and the application scene of the lithium ion battery can be favorably expanded.

The invention discloses a preferable ceramic isolating membrane prepared by porous ceramic powder.A ceramic coating mainly containing the porous ceramic powder is coated on a diaphragm.

According to the preparation method of the ceramic isolating membrane, the pore closing agent is required to be added before the slurry is prepared, and the pore closing agent is used for carrying out pore closing treatment on the porous ceramic powder in advance. It is further preferable that the hollow alumina microspheres are used as a ceramic raw material, and an extractant is adopted for leaching the coated isolating membrane to clean adsorbates of the porous ceramic isolating membrane.

In the above method, it is further preferable that the pore closing agent is an organic substance insoluble in polyethylene, polypropylene and a fiber structure polymer, and may be one or more of a plasticizer (e.g., di (2-ethylhexyl) phthalate (DEHP), dioctyl phthalate (DOP), dibutyl phthalate, diisobutyl phthalate (DIBP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), and a silicone oil (e.g., amino silicone oil, methyl silicone oil, amino modified silicone oil).

Preferably, the leaching process in the above method is an extraction process, and mainly comprises extracting the plasticizer, the silicone oil and other pore-closing agents with isopropanol, absolute ethanol and the like to form a porous carrier liquid structure again. Preferably, the extraction solution is treated to obtain the obturator agent and the solvent which need to be recycled.

In the above-mentioned method for producing a ceramic separator, it is preferable that the porous ceramic powder has been made of at least one of α -type or γ -type alumina, silica, baume, titania and the like, and has a particle diameter D_v50When the particle size is 0.5 to 150 μm, ceramic powder having a particle size of more than 4.5 μm is further pulverized to an acceptable particle size by a dry pulverizer or a wet sand mill.

The preparation method of the preferable ceramic isolating membrane provided by the invention comprises the following steps:

a) and (4) surface treatment of the porous ceramic powder. The porous ceramic powder with qualified granularity and the obturator are uniformly mixed, so that the surface defects of the powder are reduced.

b) Pulping. Fully mixing the porous ceramic powder processed in the step a), an adhesive, a thickening agent and the like to prepare slurry with certain viscosity.

c) And (4) coating. Uniformly coating the slurry prepared in the step b) on a high-molecular porous diaphragm and drying.

d) And (4) leaching. And c) carrying out solvent extraction on the dried isolation film and drying.

e) And (6) rolling. And d) releasing the stress of the dried isolation film in the d) and winding the isolation film into a finished product.

It is preferred for the above preparation process that the weight ratio of filler to obturator is from 50 to 90:10 to 50.

Preferably, the adhesive is one or more of styrene-butadiene latex, polyethylene dinitrile and modified substances thereof. The thickening agent is one or more than one of sodium carboxymethyl cellulose, sodium carboxyethyl cellulose and the like. The combined amount of the two is 2.0-9.0% by effective weight.

For the preparation method, the coating means coating the single side or double side of the isolating membrane by printing, leaching, spraying, extrusion coating and the like, wherein the coating thickness is 0.5-5.0 mu m.

Preferably, the coating process further comprises a drying process, the temperature of the drying clean air is 40-95 ℃, and the stress of the isolation film can be synchronously eliminated by adopting step temperature.

It is preferable for the above preparation method that the winding process requires tension control and the tensile strength is 2 to 10N/m.

Preferably, the isolating membrane is a dry-stretched or wet-leached isolating membrane and a fiber isolating membrane prepared by spinning, and the isolating membrane is made of high molecular polymer and has a thickness of 4-30 μm.

The present invention will be described in further detail with reference to specific embodiments.

Table 1 information on materials used in examples of the present invention

Table 2 device information used in the present invention

Example 1

42.3kg of alpha-type aluminum oxide (D) was weighed_v50：0.2μm，Al₂O₃alpha-Al in powder₂O₃The content is as follows: 95 percent; al (Al)₂O₃Powder on dry matter content of coating composition on separator: 92.09 wt%) was charged into a 100L kneader, 3.2kg of di (2-ethylhexyl) phthalate (DEHP) was added with stirring and stirred at 40rpm for 30min to obtain a closed porous ceramic composite No. 1.

Adding 70kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 1.5kg of sodium carboxymethylcellulose and 0.5kg of polyvinylidene fluoride (Solef6020) powder, fully dispersing and dissolving, adding the composite material 1# into the stirring tank after the dissolution is finished, continuously stirring for 60min, adjusting the rotating speed to 20rpm, adding 3.4kg of styrene-butadiene latex (with the solid content of 48 wt%), stirring for 30min, and filtering by a 200-mesh screen to obtain the coating slurry. The slurry was introduced into a 5-segment anilox coater trough with a diaphragm pump, the coater oven temperature was set at 50 ℃, 70 ℃, 85 ℃, 90 ℃, 75 ℃, and a wet-process diaphragm (SKLIBS) with a thickness of 12 μm was coated at a coating speed of 5m/min and dried and wound.

Unwinding the isolating membrane, taking acetone as an extracting agent, sequentially introducing the unwound isolating membrane into 5-level (namely 5 leaching tanks connected in series) leaching tanks to leach to remove a closed pore agent, drying and winding the treated isolating membrane by an oven (the tensile strength is 3N/m), and obtaining the single-side coated porous ceramic isolating membrane with the thickness of 16 mu m.

Example 2

55.8kg of gamma-type aluminum oxide (D) was weighed_v50：1.8μm，γ-Al₂O₃The content is as follows: 97 percent; al (Al)₂O₃Powder on dry matter content of coating composition on separator: 92.14 wt%) in a 100L fusion machine, adding dioctyl phthalate (DOP) pore-closing agent 4.3kg, starting the fusion machine to disperse for 20min to obtain the closed porous ceramic composite material 2 #.

Adding 79kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 1.9kg of sodium carboxymethylcellulose and 0.7kg of polyvinylidene fluoride (KYNAR 761) powder into the stirring tank, fully dispersing/dissolving, adding the composite material No. 2 into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 4.5kg of styrene-butadiene latex, stirring for 30min, filtering by using a 200-mesh screen to obtain coating slurry, introducing the slurry into a trough of a 5-stage dip-coating type coating machine by using a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃ and 75 ℃, coating, drying and rolling a dry diaphragm (CD16B) with the thickness of 16 mu m at the coating speed of 4.5 m/min.

Unwinding the isolating membrane, taking absolute ethyl alcohol as an extracting agent, sequentially introducing the unwound isolating membrane into a 5-stage leaching tank for leaching to remove a obturator, and drying and winding the diaphragm by an oven (the tensile strength is 10N/m) to obtain the double-coated porous ceramic isolating membrane with the thickness of 22 mu m.

Example 3

57.5kg of amorphous aluminum oxide (D) are weighed_v50: 2.3 μm, purity: 99.5 percent; al (Al)₂O₃Powder on dry matter content of coating composition on separator: 86.6 wt%), 3.5kg fumed silica (D)_v50: 0.1 μm, gas phase twoSilica content of coating composition on separator dry matter: 5.3 wt%) in a 100L high-speed dispersion machine, adding 5.3kg of methyl silicone oil obturator, starting the high-speed dispersion machine to disperse for 50min to obtain a closed porous ceramic composite material No. 3.

Adding 86kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 2.1kg of sodium hydroxyethyl cellulose and 0.8kg of polyethylene-vinylidene fluoride copolymer powder (2801-00) into the stirring tank, fully dispersing/dissolving, adding the composite material No. 3 into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 5.2kg of styrene-butadiene latex, stirring for 30min, filtering through a 200-mesh screen to obtain coating slurry, introducing the slurry into a trough of a 5-stage spray coating machine by using a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃ and 75 ℃, coating and winding a wet-process diaphragm (NW0735) with the thickness of 7 mu m at the coating speed of 4.5 m/min.

Unwinding the coated isolating membrane, taking anhydrous isopropanol as an extracting agent, sequentially introducing the unwound isolating membrane into a 5-stage leaching tank for leaching to remove a obturator, and drying and winding the unwound isolating membrane by an oven (the tensile strength is 2N/m) to obtain the single-side coated porous ceramic isolating membrane with the thickness of 10.8 microns.

Example 4

60.0kg of a ceramic pigment (yellow) (particle size D) was weighed_v50: 100 μm; ceramic pigment dry content of coating composition on separator: 92.9wt percent), adding 40kg of deionized water, continuing stirring for 60min, guiding the slurry into a sand mill by a diaphragm pump for circulating dispersion for 240min, and detecting that the granularity of the slurry is qualified (D)_v50: 3.0 μm) to obtain paste slurry. Filtering the slurry with 400 mesh sieve, drying at 60 deg.C for 180min under normal pressure, pulverizing with jet mill (rotating speed of 250rpm, gas pressure of 8kg) to 45 deg.C, collecting, and pulverizing into powder_v50: 2.8 μm) into a 100L high-speed dispersion machine, adding 5.9kg of ethyl silicone oil obturator, starting the high-speed dispersion machine to disperse for 50min, and obtaining the closed porous ceramic composite material No. 4.

Adding 80kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 2.1kg of sodium carboxymethylcellulose and 0.6kg of polyethylene-vinylidene fluoride copolymer powder (LBG MG-15PWD) into the stirring tank, fully dissolving, adding the composite material No. 4 into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 5.2kg of styrene-butadiene latex, stirring for 30min, filtering by a 200-mesh screen to obtain coating slurry, guiding the slurry into a trough of a 5-section extrusion type coating machine by a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃ and 75 ℃, coating and rolling a wet-process diaphragm (NW0938) with the thickness of 10 mu m at the coating speed of 4.5m/min, and uncoiling and coating the other side after coating the first side.

Unwinding the isolating membrane, taking isopropanol as an extracting agent, sequentially introducing the unwound isolating membrane into a 5-stage leaching tank for leaching to remove a obturator, and drying and rolling the unwound isolating membrane by an oven (the tensile strength is 4N/m) to obtain the double-coated porous ceramic isolating membrane with the thickness of 15 mu m.

Example 5

42.3kg of ceramic pigment (Red) (particle size D) was weighed_v50: 70 μm; ceramic pigment dry content of coating composition on separator: 89.9wt percent), adding 30kg of deionized water, continuously stirring for 60min, guiding the prepared slurry into a sand mill by a diaphragm pump for circulating dispersion for 240min, and detecting that the granularity of the slurry is qualified (D)_v50: 3.0 μm) to obtain paste slurry. Filtering the slurry with 400 mesh sieve, drying the material by vacuum heating (vacuum degree of 400kpa, temperature of 60 deg.C, 180min), reducing the temperature of the dried material to 45 deg.C, pulverizing with cyclone vortex pulverizer (rotation speed of 700rpm), collecting the powder (particle diameter: D)_v50: 3.2 μm) is added into a 100L high-speed dispersion machine, then 3.1kg of dibutyl phthalate obturator is added, and the high-speed dispersion machine is started to disperse for 50min, thus obtaining the closed porous ceramic composite material No. 5.

Adding 65kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 1.8kg of sodium carboxymethylcellulose powder and 0.8kg of polyethylene-polyvinylidene fluoride copolymer (2801-00) into the stirring tank, fully dispersing/dissolving, adding the composite material No. 5 into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 4.5kg of styrene-butadiene latex, stirring for 30min, filtering by a 200-mesh screen to obtain coating slurry, guiding the slurry into a trough of a 5-section extrusion type coating machine by using a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃ and 75 ℃, coating and rolling a dry PP/PE/PP three-layer diaphragm (M825) with the thickness of 16 mu M at the coating speed of 4.5M/min, and uncoiling and coating the other side after coating the first side.

Unwinding the isolating membrane, taking anhydrous isopropanol as an extracting agent, sequentially introducing the unwound isolating membrane into a 5-stage leaching tank for leaching to remove a obturator, and drying and winding the unwound isolating membrane by an oven (the tensile strength is 5N/m) to obtain the double-coated porous ceramic isolating membrane with the thickness of 22 mu m.

Example 6

60.9kg of ceramic pigment (blue) (particle size D) was weighed_v50: 90 mu m; ceramic pigment dry content of coating composition on separator: 91.5 percent by weight), 40kg of deionized water is added, the stirring is continued for 60min, then the slurry is led into a sand mill by a diaphragm pump for circulating dispersion for 240min, and the granularity of the slurry is detected to be qualified (D)_v50: 3.0 μm) to obtain paste slurry. Filtering the slurry with 400 mesh sieve, drying the material by vacuum heating (vacuum degree of 400kpa, temperature of 60 deg.C, 180min), reducing the temperature of the dried material to 45 deg.C, pulverizing with cyclone vortex pulverizer (rotation speed of 250rpm, gas pressure of 8kg), collecting the powder (particle diameter D)_v50: 2.8 μm) into a 100L fusion machine, adding 5.5kg of obturator agent diisononyl phthalate (DINP), opening the fusion machine to disperse for 30min, and discharging to obtain 6# of closed porous ceramic composite material.

86kg of deionized water is added into a 200L double-planet stirring tank with cooling circulating water, 2.5kg of sodium carboxymethylcellulose powder and 0.6kg of polyethylene-vinylidene fluoride copolymer (2801-00) are added into the stirring tank to be fully dissolved, after the dissolution is finished, the composite material No. 6 is added into the stirring tank to be continuously stirred for 90min, then the rotating speed is adjusted to 20rpm, 5.4kg of styrene-butadiene latex is added to be stirred for 30min and filtered by a 200-mesh screen to obtain coating slurry, the slurry is led into a 5-section extrusion type coating machine trough by a diaphragm pump, the drying oven temperature of the coating machine is set to be 50 ℃, 70 ℃, 85 ℃, 90 ℃ and 75 ℃, a wet-process diaphragm (NW0938) with the thickness of 10 mu m is coated and wound at the coating speed of 4.5m/min, and the other side is unwound and coated after the first side is coated.

Unwinding the coated isolating membrane, taking anhydrous isopropanol as an extracting agent, sequentially introducing the unwound isolating membrane into a 5-stage leaching tank for leaching to remove a obturator, and drying and winding the unwound isolating membrane by an oven (the tensile strength is 6N/m) to obtain the double-coated porous ceramic isolating membrane with the thickness of 14 microns.

Comparative example 1

The wet separator of example 1 having a thickness of 12 μm was used.

Comparative example 2

The dry separator of example 2 having a thickness of 16 μm was used.

Comparative example 3.

The wet separator of example 3 was used with a thickness of 7 μm.

Comparative example 4

The wet separator of example 4 having a thickness of 10 μm was used.

Comparative example 5

Dry PP/PE/PP three-layer separator with a thickness of 16 μm in example 5.

Comparative example 6

Example 6 a wet separator with a thickness of 10 μm.

Comparative example 7 preparation of a separation Membrane Using an unblocked porous ceramic

Comparative example 7-1 isolating film prepared by adding same amount of adhesive

Adding 86kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 2.1kg of sodium hydroxyethyl cellulose and 0.8kg of polyethylene-polyvinylidene fluoride copolymer powder (2801-00) into the stirring tank, fully dispersing/dissolving, adding 42.3kg of alpha-type aluminum oxide into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 5.2kg of styrene-butadiene latex, stirring for 30min, filtering by a 200-mesh screen to obtain coating slurry, guiding the slurry into a trough of a 5-section spray coating machine by using a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃, 75 ℃, and coating and rolling a wet-process diaphragm with the thickness of 7 mu m at the coating speed of 4.5 m/min. (tensile strength 3N/m) to obtain a single-side coated porous ceramic separator having a product thickness of 10.8. mu.m. The phenomenon of coating shedding and coating dusting occurs when the isolating membrane is uncoiled, and the isolating membrane cannot be put into practical application.

Comparative example 7-2 performance of barrier film prepared by adding excess adhesive

Adding 86kg of deionized water into a 200L double-planet stirring tank with cooling circulating water, adding 2.1kg of sodium hydroxyethyl cellulose and 0.8kg of polyethylene-polyvinylidene fluoride copolymer powder (2801-00) into the stirring tank, fully dispersing/dissolving, adding 42.3kg of alpha-type aluminum oxide into the stirring tank after the dissolution is finished, continuously stirring for 90min, adjusting the rotating speed to 20rpm, adding 10.2kg of styrene-butadiene latex, stirring for 30min, filtering by a 200-mesh screen to obtain coating slurry, guiding the slurry into a trough of a 5-segment spray coating machine by using a diaphragm pump, setting the drying oven temperature of the coating machine at 50 ℃, 70 ℃, 85 ℃, 90 ℃, 75 ℃, and coating and rolling a wet-process diaphragm with the thickness of 7 mu m at the coating speed of 4.5 m/min. (tensile strength 5N/m) to give a single-side coated porous ceramic separator having a product thickness of 11.2. mu.m.

Example 8SEM analysis

The separators of example 2, example 3, comparative example 2 and comparative example 3 were subjected to electron microscope analysis at a magnification of 20000 times to obtain the results of FIGS. 1-a to 1-d.

As can be seen from the drawings 1-a and 1-b, the surfaces of the embodiment 2 and the embodiment 3 are covered with a layer of ceramic powder, the size of the powder is uniform, the particle size of the prepared ceramic powder composition is 1-3 μm, meanwhile, as can be seen from the drawings 1-a and 1-b, part of the powder is slightly bonded in an electron microscope to form a state similar to 2-time particles, but the bonding degree is relatively light, the particle size of the aggregate is less than or equal to 5 μm, and simultaneously, as can be seen from the drawings 1-c, the comparative example 2 is a diaphragm prepared by a dry method, the pores are generated in a stretching state, the local part of the diaphragm is in a non-porous continuous state, the generated pores are elliptical micropores, and the forming directions of the pores are consistent. As can be seen from fig. 1-d, comparative example 3 was prepared by wet extraction, and the pores were in a disordered state, and the pore size was smaller than that of the dry method, and the pore distribution was more uniform.

Example 9 shrinkage testing

The coated release films prepared in examples 1 and 5, the uncoated release film in comparative examples 1 and 5 and the uncoated release film in comparative examples 7-2 were unwound for 2m, then a square sample of 48cm (reel direction) by 32.5cm (unwinding direction) was punched in the unwinding direction, and then the square sample was placed flat in an oven and subjected to baking tests at 60 ℃ ± 2 ℃/36h and 110 ℃ ± 2 ℃/1, and after the baking was finished, the sample was taken out and the lengths of the sample in the unwinding direction and the axial direction were remeasured, and the results in table 3 were obtained.

TABLE 3 results of heat shrinkage test of examples

As can be seen from table 3, with respect to the prepared separator, the baking shrinkage rate at 60 ℃, the coated separators (examples 1, 5 and comparative examples 7-2) were slightly smaller than the uncoated separators (comparative examples 1, 5) but were substantially in the same order of magnitude (within 5%). However, when the temperature was increased to 110 ℃, the shrinkage of the coated separator was within 10%, but the shrinkage of the uncoated separator was 35% or more, and it can be seen from table 3 that the shrinkage of the wet separators (example 1, comparative example 1) was slightly less than that of the dry separators (example 5, comparative example 5) at 60 ℃, mainly because the dry separators were prepared by a film stretching method, internal stress was concentrated in the separators, and when the temperature was increased, molecular movement in the polymer chain was increased, resulting in release of the internal stress and greater shrinkage. As can be seen from table 3, the porous ceramic separator prepared by the present invention does not substantially shrink at high temperature (the same is true for comparative examples 7-2), which greatly increases the safety of the lithium ion battery during the preparation and use of the lithium ion battery, and at the same time, since the separator contains the polymer compounds (polyvinylidene fluoride polymers and copolymers) capable of absorbing the electrolyte and swelling after long-term soaking, it is possible to interact with and adhere to the polymer compounds of the same composition in the electrode sheet, thereby reducing the slip between the sheets and accordingly improving the "hardness" of the lithium ion battery.

Example 10 porosity

The porosity and pore size distribution of the separators prepared in example 5, example 6, comparative example 5 and comparative example 6 were measured by mercury intrusion porosimetry, and the results shown in fig. 2 were obtained.

As can be seen from fig. 2, comparative example 5 is a dry three-layer separator, which has a large pore size and a wide distribution, and after porous ceramic coating, the pore size of example 5 is reduced and the pore size distribution is slightly concentrated, which actually shows the pore size distribution of the porous ceramic coating loaded on the polymer separator, and a small number of small peaks appear in the small pore size region, and the radius of lithium ions is usually 0.076nm, and the pore size corresponding to the small peaks can also ensure that lithium ions freely pass through the barrier film coating. Similarly, for example 6, the porous ceramic coating changes the narrow pore size distribution of the original wet-process separator, the pore size distribution range is enlarged, the porous ceramic coating is basically similar to that of example 5, the pore size distribution characteristics of the porous ceramic coating are all reflected, and the wide pore size distribution is also beneficial to the electrolyte absorption capacity of the separation membrane, so that the coating of the example can meet the use requirements of the lithium ion battery.

EXAMPLE 11 wetting Angle

The separators of example 5, example 6 and comparative example 5, comparative example 6 and comparative example 7-2 were cut into small pieces and placed on an electron microscope stage using an electron microscope, the electrolyte was dropped on the separator under magnification after the electrolyte was absorbed by a pick-up card, and the wetting angle of the drop was tested after waiting for 20 seconds. The results of Table 4 were obtained.

Table 4 example wetting angle test results

Examples	Wetting corner (o)
		Comparative example 5	50.9
Comparative example 6	39.8
		Example 5	15.1
Example 6	10.9
		Comparative examples 7 to 2	40.2

As can be seen from table 4. The diaphragm of the comparative example 5 or 6 is made of polyethylene or polypropylene, so that the wettability of the diaphragm to the electrolyte is poor, the electrolyte is in a liquid drop state on the isolation surface, after the porous ceramic powder coating treatment is performed on the diaphragm, the electrolyte liquid quickly spreads on the isolation membrane to form a circle with a larger radius, and the wetting angle is rapidly reduced to be within 20 degrees, so that the wetting performance of the isolation membrane is greatly improved, and the wetting angle of the diaphragm of the comparative example 7-2 is larger despite the coating treatment, so that the pores on the surface of the coating are possibly sealed by the adhesive due to excessive addition of the adhesive, and the wetting and the diffusion of the organic electrolyte are not facilitated.

Example 12 preparation of symmetrical Battery EIS

Punching a positive plate coated on one side into single-piece pole pieces (the size of the pole piece is 32 x 48mm) by adopting a TU-50 type manual punching machine according to different directions of a pole lug, punching isolating films in an example 3, a comparative example 3 and a comparative example 7-2 into small pieces of 35 x 52mm, overlapping the positive plate, the isolating film and the positive plate together, fixing the small pieces by using an electronic adhesive tape, packaging the small pieces by using an aluminum plastic film on three sides, putting the small pieces into a vacuum drying box for drying (85 ℃/16h, the vacuum degree is-0.08 KPa, ventilating every 4 h), taking out the small pieces after drying, cooling, injecting 0.5g of electrolyte, packaging, standing the small pieces at normal temperature for 2h, and performing electrochemical impedance spectrum test by adopting an electrochemical workstation to obtain results shown in a table 5 and a figure 3.

Table 5 example electrochemical impedance spectroscopy results for symmetric cells

As can be seen from table 5 and fig. 3, in comparative example 7-2, compared to comparative example 3, the ac impedance (938.7m Ω) and the dc impedance (1737.7m Ω) were not greatly reduced, while the semicircular rings of the separator not coated in comparative example were still preserved, indicating that the performance of the separator was not greatly changed by coating the ceramic powder that was not subjected to sealing treatment, and the effect of improving the internal resistance characteristics of the lithium ion battery was not achieved. The EIS curve corresponding to example 3 is greatly changed, and the semicircular ring disappears, which indicates that the ion channel characteristics of the symmetric battery are greatly improved, so that the ceramic isolation membrane of the present invention is favorable for improving the performance of the lithium ion battery.

In summary, the present invention provides a method for preparing a porous ceramic isolation membrane and a composition thereof, and the basic physical and chemical properties and beneficial results of the preparation thereof, which are limited by space and experimental demonstration, and the porous ceramic isolation membrane of the present invention can promote the improvement of the comprehensive properties of a lithium ion battery, expand the application range of the lithium ion battery, and is beneficial to the related technology development, and is not limited to the above specific embodiments, and all the disclosed and undisclosed cases do not affect the essence of the present invention.

Claims

1. A preparation method of a ceramic isolating membrane comprises the following steps:

step a) pulping, namely fully mixing raw materials containing a closed porous ceramic composite material, a binder and a thickening agent to obtain slurry;

wherein step d) may be omitted; wherein the open pores of the porous ceramic are filled and sealed by organic matters;

the organic matter is selected from a plasticizer and/or silicone oil.

2. The production method according to claim 1, wherein the porous ceramic is selected from one or two or more of oxides, nitrides, carbides, fluorides, carbonates, and phosphates.

3. The production method according to claim 1, wherein the porous ceramic is selected from one or more of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, barium oxide, magnesium oxide, yttrium oxide, samarium oxide, ytterbium oxide, boehmite, titanium nitride, aluminum nitride, silicon nitride, calcium phosphate, silicon carbide, and magnesium fluoride.

4. The production method according to claim 1, wherein the porous ceramic is selected from alumina and/or silica.

5. The production method according to claim 1 or 2, wherein the particle size of the porous ceramic is 4.5 μm or less.

6. The production method according to claim 1 or 2, wherein the particle size of the porous ceramic is selected from 0.2 to 4.5 μm.

7. The production method according to claim 1 or 2, wherein the particle size of the porous ceramic is 0.5 to 2.3 μm.

8. The production method according to claim 1, wherein the plasticizer is selected from a carboxylic acid ester and/or a phosphoric acid ester; the silicone oil is selected from one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, methyl phenyl silicone oil, methyl chlorphenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoro propyl silicone oil, methyl vinyl silicone oil, methyl hydroxyl silicone oil, ethyl hydrogen-containing silicone oil, hydroxyl hydrogen-containing silicone oil, cyanogen-containing silicone oil, amino modified silicone oil, epoxy modified silicone oil, polyether modified silicone oil, carboxyl modified silicone oil, alcohol light-group modified silicone oil and phenol light-group modified silicone oil.

9. The method according to claim 1, wherein the silicone oil is one or more selected from the group consisting of methyl silicone oil, ethyl silicone oil, and amino silicone oil.

10. The production method according to claim 1, wherein the plasticizer is one or more selected from the group consisting of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diisobutyl phthalate, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, di (2-ethylhexyl) phthalate, tributyl phosphate, triethyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, diisononyl adipate, and di (2-ethylhexyl) adipate.

11. The method according to claim 1, wherein the plasticizer is one or more selected from the group consisting of di (2-ethylhexyl) phthalate, dioctyl phthalate, dibutyl phthalate and diisononyl phthalate.

12. The production method according to claim 1 or 2, wherein the binder is one or more selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene ethylene copolymer, styrene-butadiene latex, polyacetonitrile, polymethyl methacrylate, polyamide, gelatin, polyvinyl alcohol, polyacrylate, and polyacrylic acid.

13. The method of claim 1 or 2, wherein the binder is selected from polyvinylidene fluoride and/or styrene-butadiene latex.

14. The production method according to claim 1 or 2, wherein the thickener is one or more selected from the group consisting of a polyacrylate, an acrylic acid copolymer, polyvinylpyrrolidone, a cellulose-based compound, and polyacrylamide.

15. The production method according to claim 1 or 2, wherein the thickener is one or more selected from the group consisting of methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, and hydroxypropylmethylcellulose.

16. The production method according to claim 1 or 2, wherein the separator is one or two or more selected from a dry-drawn separator, a wet-leached separator, and a textile-produced fibrous separator.

17. The production method according to claim 1 or 2, wherein the separator is one or more selected from the group consisting of polyolefin, polyamide, polyester, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride.

18. The production method according to claim 1 or 2, wherein the thickness of the separator is 4 to 30 μm.

19. The method of claim 1, wherein the thickener is added in an amount of 2 to 5wt% of the closed porous ceramic composite.

20. The method of claim 1, wherein the thickener is added in an amount of 3 to 4wt% of the closed porous ceramic composite.

21. The method of claim 19, wherein the closed porous ceramic composite comprises 89-93wt% of the dry matter content of the coating composition on the separator.

22. The preparation method according to claim 1, wherein in the step b), the coating is selected from one or more of printing, dipping, spraying and extruding.

23. The production method according to claim 1, wherein in the step b), single-sided or double-sided coating is performed on the separator.

24. The method according to claim 1, wherein the coating thickness obtained by drying in step b) is 0.5 to 5.0 μm.

25. The preparation method according to claim 19, wherein in the step b), the coating is selected from one or more of printing, dipping, spraying and extruding.

26. The production method according to claim 19, wherein in the step b), single-sided or double-sided coating is performed on the separator.

27. The method as set forth in claim 19, wherein the coating thickness obtained by drying in the step b) is 0.5 to 5.0 μm.

28. The preparation method according to claim 21, wherein in the step b), the coating is selected from one or more of printing, dipping, spraying and extruding.

29. The production method according to claim 21, wherein in the step b), single-sided or double-sided coating is performed on the separator.

30. The method as set forth in claim 21, wherein the coating thickness obtained by drying in the step b) is 0.5 to 5.0 μm.

31. The production method according to claim 1, wherein the solvent is one or more selected from acetone, ethanol, butanol, and/or isopropanol.

32. The production method according to claim 19, wherein the solvent is one or more selected from acetone, ethanol, butanol, and/or isopropanol.

33. The production method according to claim 21, wherein the solvent is one or more selected from acetone, ethanol, butanol, and/or isopropanol.

34. The production method according to claim 22, wherein the solvent is one or more selected from acetone, ethanol, butanol, and/or isopropanol.

35. The method of claim 1, wherein the drying in step b) is oven drying.

36. The method of claim 35, wherein the drying is performed with clean air at a temperature of 40-95 ℃.

37. The preparation method according to claim 1, wherein the winding in the step d) adopts tension control.

38. The production method according to claim 37, wherein the tensile strength is 2 to 10N/m.

39. A ceramic separator produced by the production method according to any one of claims 1 to 38.

40. A lithium ion battery comprising the ceramic separator according to claim 39.

41. Use of the ceramic separator of claim 39 or the lithium ion battery of claim 40 in the field of energy.